Excavating-machine



W. H. RODDA.

BXGAVATING MACHINE.

(No Model.)

Patented Dee. 20,1881.

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UNITED STATES PATENT OEErcE.

WILLIAM H. RODDA, OF DETROIT, MICHIGAN.

EXCAVATlNG-MACHINE.

SPECIFICATION forming part of Letters Patent No. 251,291, dated December 20, 1881.

Application filed Octoberl, 1881. (No model.)

To all whom it may concern Be it known that I, WiLLIAM H. Renna, of Detroit, in the county of Wayne and State of Michigan, have invented an Improvement in Excavatiiig-ll/Iachines, of which the following is a specification.

The nature of this invention relates to certain new and useful improvements in the coil- V tially as hereinafter described.

Figure lis an elevation in vertical longitudinal section; and Fig. 2 is an enlarged detail, partially in section. Fig. 3 is a top plan of the mast.

In the accompanying` drawings, which form a part of this speciicatiol'i, A represents the upper rail, and B the lower rail, of a boom for an excavating-machine. The rail A is supported at one end upon trunnions G, having bearingsin the circular box D, which is sleeved upon the vertical shaft or mast E, resting upon a shoulder, F, thereon,-in such a manner that said rail A may-have both a vertical movement upon its trunnions and a rotary horizontal movement upon the circular box D.

H isa brace and tiered, one or more of which, as is necessary, are employed to support the vertical mast E. The lower end of this mast is rigidly secured to a platform, P, iu any desired manner.

The rail B of the boom, at its outer end, is rigidly secured to the rail A. The opposite end of this rail is curved upon a circle the center of which is in the axis ofthe trunnions C, upon which the rail A is supported. This rail B is made in two parts, as shown in Fig. 2, so that its free ends a will embrace the flanged slide-block I, to which is rigidly secured the semicircular turn-table J; and through the slide and turn-table is a bore, K, through which the bottom of the mast passes, such bore allowing the turn-table and slideto rotate upon the mast. The periphery of this Aturn table J is provided with a rack, L, which engages with a pinion,

M, at the end of a shaft, to which any suitable power is applied for operatin g such turn-table. The free ends a of the rail B embrace the sides of the slide I, vwhich is provided with flanges b to guide the rail B.

N are angle-irons fitting between the two sides of the rail B, to which such angle-irons are secured by suitablebolts and nuts. When thus secured in place, the exposed dat face of such angle-iron abuts against the front c ofthe slide and converts the rail B into a brace for the rail A. It frequently becomes necessary, when such boom is secured to a car, that the outer end thereof should be' adapted to belowered to the plane of the top of the mast in order to pass under bridges over a railway-track.

This has heretofore been accomplished by removing the braces and uuscrewing the nuts which connect the outer end of the boom-rails to allow the same to be lowered.

To obviate the diliiculties heretofore found in the construction ot excavators, I provide the slide and the peculiar construction ofthe curved rail-brace B, so that bysimply removing the angle-ironsNthe end of the boom may be lowered the required distance, the sides of the rail embracing and being guided in such movement by the slide I. To limitand regulate this movement I provide a screw, O, and a nut, P, which nut is provided with trunnions d upon each side, which trunnions have bearings in the two parts ofthe rail B. The free end of this screw passes between the angle-irons N, as shown in Figs. 1 and 2, and impinges against the front of the slide. The angle-irons being removed,

the screw still upholds the boom, and on ruuuiug the screw up or down then raises or low- -ers the outer end of the boom. When raised to its desired position the angle-irons are put in place and secured, in order to furnish amore firm bearing, for without ita heavy strain upon the outer end of the boom would have a tendency to bend the screw, and the angle-irons relieve the strain upon the end of the screw, except when such irons are removed for the purpose of adj usting vertically the end of such boom. The rail Bis provided with a series of bolt-holes, n, to allow the adjustubility of the augle-irons at any desired point.

What I claim as my invention is 1. A boom for an excavator, the upper rail of which is adapted to move vertically and lat- IOO erally upon a radius from the mast, such vernut P, and angle-irons N, the parts being contieal radial movement being controlled and strueted,arranged,andoperatngsubstantially limited by the rail B, constructed substantially as and for the purposes described. as described, and the slide I, substantially as 4. Inavertieally-adjustable boorn,the curved 5 and for the purposes specified. lower rail, B, provided with adjustable angle- 2. In aboom foran excavating-machine, and irons N, as and for the purposes shown and as alneans for controlling the movements of described. rthe lower rail of said boorn, the slide I and turntable J upon the foot ofthe mast, substantially 1o as set forth. Witnesses:

3. The combination of the rails A B, trun- H. S. SPRAGUE, nions C, box 1), turn-table J slide I, screw O, E. SGULLY.

WILLIAM H. RODDA. 

